Why can’t my heat pump keep up with my thermostat

You set your thermostat for 71 degrees and your house only seems to get up to 68 degrees. Why can’t my heat pump keep up with my thermostat? This is a very common problem and generates many service calls. Sometimes, it is caused by a genuine problem. Unfortunately, sometimes there is nothing you can do. Even a properly working heat pump will struggle to maintain your desired temperature.

Why is this? When it gets below a certain temperature (in the mid 30’s), heat pumps lose their efficiency and cannot keep up with the heat loss of your home. When the temperature drops approximately 2 degrees below room temperature, supplemental heat comes on to assist the heat pump (usually in the form of heat strips). When it gets to within 1.5 degrees of room temperature, the back-up heat cycles off and the heat pump continues to run – trying to reach temperature – but cannot.

This is, however, the way heat pumps are designed to operate. Even though they do not put out a lot of heat into the house, and they run for long periods of time, they are still quite efficient. So if it is very cold out, you may have to raise your thermostat by 2 degrees to maintain the temperature.

Now, if it is NOT very cold out (mid to high 30’s and above) and your heat pump is not maintaining the temperature, there is a problem! Listed here are some of the causes (and may very likely require a house call from a professional licensed HVAC technician):

  • thermostat not calibrated/not level/faulty
  • low refrigerant charge
  • refrigerant flow-related problem
  • poor efficiency – needs cleaning and/or servicing
  • bad reversing valve
  • bad compressor valves
  • compressor not running

Here are a few more problems that you may be able to resolve on your own:

  • outdoor unit iced up
  • outdoor unit not running – check your breakers to make sure they were tripped
  • return duct leakage – may need to be sealed
  • open windows or poorly insulated house

Call us here at LHT Cooling & Heating if you still can’t figure out why can’t my heat pump keep up with my thermostat!


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North Myrtle Beach HVAC & Refrigeration

LHT Cooling, Heating & Refrigeration is a North Myrtle Beach HVAC and commercial refrigeration company serving the South Carolina Grand Strand, Carolina Shores and North Carolina. LHT services and repairs heat pumps, heating units, air conditioning units, furnaces, ventilation systems, indoor air quality, humidifications, ductless systems, boilers, reach-in coolers, walk-in coolers, reach-in freezers, walk-in freezers, ice machines, blast chillers and refrigerated displays.

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